Incendiary Shotgun Challenge Tracking Bug

The Assault Class challenge that requires the player to deal damage using the Incendiary Shotgun does not track all damage done by the shotgun. It appears the challenge only tracks the damage done from the initial shot-damage, but does not track the damage done by fire effects afterwords.

I wasn't able to get a screenshot, but I dealt 100 damage total to an enemy after two shots, but the challenge only tracked 40 damage.